LOUISVILLE, Ky. (WDRB) -- Who's telling the truth? Today we will see the conclusion to the Dr. Phil series on the murder of Trey Zwicker. The 14-year old Louisville boy was found savagely beaten behind Liberty High School on May 11, 2011.

On today's show, Josh Young and his cousin, Cassi Gouker, both agree to take polygraph tests. Gouker claims Young woke her up in the middle of the night on May 10, 2011 and asked her to help him hide a murder weapon and bloody clothes. Young said he had nothing to do with the death of Zwicker, his stepbrother.

Young was acquitted at trial after his father confessed to killing Zwicker and setting his son up to take the fall.

The results of the polygraph will air today on Dr. Phil. You can see it on WDRB at 3 PM.

In Monday's Dr. Phil episode, titled, "My Father Tried to Set Me Up for Murder," there was yet another wild accusation. Josh Gouker says he acted like a monster so his son, Joshua Young, could get away with murder.

Meanwhile, Young told Doctor Phil what he didn't tell the jury: his version of what happened the day Zwicker died.

"We had a cookout and it seemed like a normal family cookout," Young said. "We played basketball and I just finished it like a normal night, and went to sleep."

"When was the last time you saw Trey?" Dr. Phil asked.

"The last time that I set eyes on Trey was when he told me he was going to go in and take a shower, and I went two doors down to my dad's cousin, Cassi's," Young replied.

But Terry Zwicker, Trey Zwicker's father, wasn't buying it.

"So you think he's involved because he lied about what happened the night Trey was murdered?" Dr. Phil asked Terry Zwicker.

"Most of the time when stories change it is a lie," Terry Zwicker said.

"Why are there two different stories?" Dr. Phil asked Young.

Terry Zwicker pointed to what he said were conflicting statements made by Young.

"The initial interview I had never had something like this happen, I was freaking out. I was at a loss for words and a loss for actions and thoughts. I did not know what to do. I'm not sure," Young replied.

Young then recalled the moments after he was arrested for killing Trey Zwicker, when he learned his father turned him in.

"In my head, I'm thinking, 'You're lying,'" Young said. "I was sitting there crying. I didn't know what was happening. I felt just like every emotion possible, for real, sadness, anger, depressed, confused, just everything all at once."

Young was acquitted for Zwicker's murder and Young's father, Josh Gouker, eventually confessed to beating his stepson to death and setting up his own son.

But Gouker's story changes again during the taping as he seeks to get his life sentence overturned.

"I think everyone knows who really killed Trey," Gouker said.

"Are you not going to answer the question honestly?" Dr. Phil asked Gouker.

"I mean they can't do anything to him -- it would be double jeopardy," Gouker said.

"By 'him,' you're referring to your son Josh?" Dr. Phil asked.

"Right," Gouker responded.

Replying to his father's claim, Young said, "I'm at a loss for words. I don't understand what this guy's problem is."

"I went on the local TV station and was just a monster because 12 of somebody watching that [expletive] was going to be in that box, and I just had to be consistently a monster," Gouker said.

"I believe he's right. He could care less what he says as far as sugar coating the truth. He'll tell you the truth. He's really too stupid to lie," Terry Zwicker said about Gouker's statement.

Terry Zwicker grew frustrated during the show, saying Young was pretending to be a choir boy, but his real character can be seen in social media.

When Dr. Phil asked Young about Zwicker's claims, Young replied, "I don't have a Facebook account."

Actually, Young has reached out to WDRB reporters several times on Facebook. His account was recently deleted.

Terry Zwicker says he just wants closure to finally know what happened to his son.

"The way I believe it happened is Joshua Gouker, Joshua Young and Trey Zwicker. They had an adult taking them down to a ditch bank to smoke a joint. Gouker hit my son in the side of the face while this young man finished it off," Terry Zwicker said.